This Program Project will explore the molecular basis for selected disorders of coagulation and thrombosis and the role of hemostatic balance in vascular disease pathogenesis. The individual projects in this proposal emphasize the use of new technologies to provide improved biologic insight and develop new treatments for hemorrhage, thrombosis and related cardiovascular disorders. The three individual projects contained in this PPG will: (1) continue a whole genome ENU mutagenesis analysis in the mouse to identify genetic modifiers of factor V Leiden, while also taking advantage of natural murine strain variation to identify additional thrombosis modifiers, as well as modifier genes for thrombotic thrombocytopenic purpura (TTP);(2) continue to explore the critical factors that limit factor VIII expression. The current proposal focuses on the molecular mechanisms responsible for the oxidative stress that results from misfolded FVIII in the ER lumen;and (3) explore the role of bacterial streptokinase (SK) and its interaction with plasminogen in the pathogenesis of Group A streptococcal infection;high throughput chemical screening will be used to develop specific SK inhibitors as a potential new class of antibiotics for this important human infection. The PPG will continue to support 4 cores: (A) the Mouse Coagulation Laboratory, (B) the Genetics Core, (C) the Administrative Core, and (D) the Morphology Core. The PPG will aim to increase interaction and collaboration between individual project participants, as well as among the large number of other laboratories at the University of Michigan already engaged in research on coagulation, thrombosis and vascular disease. We anticipate that the overall program resulting from the combined efforts of all participants will significantly exceed the sum of the individual parts. Relevance to public health: Abnormalities in the control of blood clotting are a critical factor in a number of diseases, including heart attack and stroke (the leadings causes of death in the US), as well as several important infectious diseases. This Project will identify key genes in this system that should provide valuable new diagnostic tools as well as suggest novel approaches to treatment.